"Bernie Sanders has laid out a very expensive program," the longtime Democrat told Jake Tapper on CNN. "It's a $33 trillion program with 20 new taxes to support it.

"I don't believe it's going to happen — but people want change, which I understand, and they want government to do more to secure that change," said Feinstein, a Hillary Clinton supporter. "I'm not for socialized medicine, have never been and never will be — so single-payer takes us right into that arena.

"I don't see it going anywhere."

Feinstein, 82, who was first elected in 1991, said that the federal government also needed to stay out of state university systems, including the 238,700-student University of California.

"The state legislature and the governor fund it, plus tuition," she told Tapper. "I don't believe the federal government should step in and begin to fund that tuition.

"We already put in about $9 billion in California to the university in the form of many land grants."

Feinstein also praised Clinton's speech attacking presumptive Republican nominee Donald Trump in San Diego. The Golden State is among five holding contests on Tuesday, the last day of the 2016 primary season.

"I was very proud of that speech," she said. "I was very proud of Hillary.

"I saw Hillary as president of the United States — and a president we could be proud of in that speech."